Compounds have already been proposed as sedatives which have the following general formula ##STR2## in which B is 4-chlorophenyl (German published application 20 27 051).
Other compounds of this general type are described in U.S. Pat. No. 3,637,704 to Umemoto as having the following formula: ##STR3##
In a variant of this compound described in the same patent, the methoxy group is replaced by a 4-fluorobenzyl group.
Other piperazines of the fluorobenzoylpropyl substituted type have been disclosed in the above identified parent application, Ser. No. 589,121. Among these compounds was the compound of the present application.